1. Field of the Invention
The present invention relates generally to an accessory apparatus of a mobile terminal, and in particular, to an accessory apparatus for receiving digital multimedia broadcasting (DMB) data.
2. Description of the Related Art
In general, digital multimedia broadcasting (DMB) is a service that provides high image and sound quality, and improved service to users by replacing conventional analog broadcasting. Recently, as the digital broadcasting and mobile communication technologies have evolved, users have become increasingly interested in digital broadcasting service for watching a digital broadcasting program while in motion. Thus, at present, an omni-directional DMB receive antenna is installed in a mobile terminal, and DMB data can be received using such a mobile terminal (hereinafter DMB receiving terminal).
Therefore, in order to receive DMB data, a typical mobile terminal must include a DMB receiving unit and a DMB module for decoding and reproducing the received DMB data. However, since the typical mobile terminal does not include these components, a user cannot watch a DMB program using the typical mobile terminal.
Mobile terminals currently on the market, such as mobile phones and Personal Digital Assistants (PDAs), have an accessory interface. An accessory is a peripheral device, such as an ear-mike or an earphone jack, which can be used while connected to a mobile terminal. The accessory interface is an interface of a mobile terminal through which the accessory can be connected to the mobile terminal. Thus, a user can use a mobile terminal in various manners by connecting various accessory apparatuses to the mobile terminal through the accessory interface.
Consider the connection of an accessory apparatus, including the DMB receiving unit for receiving DMB data and the DMB module for decoding and reproducing the received DMB data, to the accessory interface of the mobile terminal. In this case, in order for the accessory apparatus to receive and reproduce DMB data, the accessory apparatus must control the mobile terminal so that the received DMB data can be reproduced in the mobile terminal after receiving the DMB data. Thus, the accessory apparatus must have a function of operating as a host device of the mobile terminal, and the mobile terminal must recognize the accessory apparatus as the host device.
However, a general accessory, such as an ear jack or a microphone, is only used to receive an audio signal output from a mobile terminal or input a voice signal to the mobile terminal through the microphone. An accessory apparatus, such as an external DMB antenna, only has a passive function of receiving DMB data in response to a control of a DMB receiving terminal and transmitting the received DMB data to the DMB receiving terminal.
An accessory interface of a general mobile terminal has terminals for data input/output signals, power and ground, and does not have a terminal, such as a V Bus terminal of a 24-pin interface, for receiving a voltage from a connected peripheral device and recognizing the peripheral device as a host or a slave.
Thus, the accessory interface of the general mobile terminal cannot recognize a connected peripheral device as a host. This is because in a method of recognizing a peripheral device as a host, which is used in the general mobile terminal, when a peripheral device, such as a personal computer having a host function, is connected to the mobile terminal, the peripheral device applies a voltage to a V Bus terminal of the mobile terminal. Then, the mobile terminal recognizes the peripheral device as a host using the voltage input through the V Bus terminal.
The mobile terminal recognizes the peripheral device as a host according to logical states of data terminals used to exchange data with the peripheral device. If the mobile terminal is connected to the peripheral device through the 24-pin interface including the V Bus terminal, the mobile terminal applies the voltage input through the V Bus terminal to any one of data terminals not used to exchange data with the peripheral device. Then, the mobile terminal recognizes the connected peripheral device as a host only if all the data terminals are logically high.
Thus, the general mobile terminal, which does not have the V Bus terminal, cannot recognize a device connected through the accessory interface as a host.